#1 - At many electronics retail stores, the consumer has the

[lanereuden]

Why is D wrong?
Some say that it could weaken argument
But to me if extended warranty incorporates manufacturer warranty (and a little bit longer), it’s not that worth it since you are paying twice...once for original manufacturer warranty and another time for extended warranty

[Adam Tyson]

You assume that the consumer is paying something for the manufacturer's warranty, lanereuden! In the real world, that's not the case - the purchase price of the product includes that warranty. The extended warranty might provide extra protection that the manufacturer's warranty does not provide, and the fact that it lasts longer might make it worthwhile. That's why some people think it might weaken the argument. Personally, I don't see it - it looks to me like it is just repeating information we already had in the stimulus.

But look at how weak answer D is, talking only about "some" extended warranties. If that helps, it doesn't help very much! Compare that to "generally" in the correct answer (meaning most of the time - more often than not), and you'll see how much more of a help that answer is. Answer D might strengthen the argument, IF you make some outside assumptions, but even then it still does not do the most to strengthen the argument when compared to the correct answer. Don't focus on whether the answer could strengthen the argument, but focus instead on whether it does more to help than the other four answers do. This is a test of comparing answers to each other, not looking at any one answer in isolation.